Synthesis gas, reducing gas, and fuel gas are gaseous mixtures comprising H.sub.2, carbon oxides, H.sub.2 O, and CH.sub.4. Synthesis gas and reducing gas are rich in H.sub.2, CO and have varying H.sub.2/ CO mole ratios. Fuel gas is rich in CH.sub.4 and has a high heat capacity. These gases are commonly made by the gasification of fossil fuels e.g. liquid hydrocarbonaceous fuels such as crude oil, and solid carbonaceous fuels such as coal and petroleum coke. Mercury contamination in the synthesis gas, reducing gas, and fuel gas occurs when the feedstock to the gasifier contains mercury. For example, reported values of mercury concentrations in coal feedstocks range from about 0.012 to 33 ppm (parts per million) with an average value of about 0.2 ppm for certain U.S. coals. When large amounts of coal e.g. about ten thousand tons per day of a coal containing about 0.25 ppm to Hg are burned upwards of 5 pounds per day of mercury would be discharged into the atmosphere posing health and environmental hazards through mercury entering the food chain. U.S. Pat. No. 4,196,173 found that it was only practical to remove mercury from air in a bed of activated carbon of critical thickness and chlorine content. In U.S. Pat. No. 4,044,098, H.sub.2 S was added to natural gas to precipitate the sulfides of mercury. The excess H.sub.2 S was absorbed by a solvent. Technology for control of mercury emissions from such large sources as coal fired furnaces has not been developed although mercury has been observed in flue gas sulfur oxide scrubber effluent liquid. In one study, about 90% of the mercury in the fuel used for a large coal fired furnace was released and appeared as vapor discharged in the stack gas.
The partial oxidation process is a well known process for converting liquid hydrocarbonaceous and solid carbonaceous fuels into synthesis gas, reducing gas, and fuel gas. See coassigned U.S. Pat. Nos. 3,988,609; 4,251,228, and 4,436,530 for example, which are incorporated herein by reference. The removal of acid-gas impurities from synthesis gas is described in coassigned U.S. Pat. Nos. 4,052,175, and 4,081,253, which are incorporated herein by reference. However, the aforesaid references do not teach nor suggest the subject process for the production of demercurized synthesis gas, reducing gas, or fuel gas. By the subject process, the amount of mercury in synthesis gas, reducing gas, and fuel gas may be reduced to a safe level to avoid contaminating the atmosphere and catalysts, and to prevent possible health problems.